Valve actuator

ABSTRACT

There is disclosed an actuator for a rotary valve, such as a butterfly valve which rotates a quarter of a turn between open and closed positions. The actuator includes a drive mechanism releasably attachable to the stem of the valve for rotating it in response to operation of a reversible electric motor.

This application is a divisional of U.S. application Ser. No.08/603,785, filed Feb. 20, 1996 and entitled "Valve Actuator".

This invention relates generally to an actuator for a rotary type valve,which, for example, may be a butterfly valve in which the valve memberis a disc generally rotatable a quarter turn between open and closedposition. More particularly it relates to improvements in rotary valveactuators in which the valve member is moved between open and closedposition by a reversible electric motor.

A rotary valve actuator of the type contemplated by this inventioncomprises a housing adapted to be mounted on the valve, a drive systemincluding a worm gear mounted for rotation in the housing and adapted tobe releasably connected to the valve stem, when the housing is mountedon the valve, in order to impart rotation thereto, a reversible electricmotor in the housing having an output shaft, a worm shaft mounted forrotation and limited reciprocation within the housing, and a meansconnecting the motor shaft to the worm shaft for rotating the worm shaftand connecting the worm shaft to the worm gear for rotating the wormgear and thus the valve stem in opposite rotational directions to openand close the valve responsive to reverse operation of the motor.

In most prior actuators of this type, the electric motor is adapted tobe deactivated in the event of excessive torque on the drive systemwhen, for example, the valve member encounters an obstruction. For thispurpose, it has been proposed to mount a worm for rotation with the wormshaft and a cam on the worm shaft adjacent the worm to engage sensors onswitches leading to the motor, when the drive system encountersexcessive torque, for deactivating the motor. More particularly, theworm and cam are disposed in neutral positions between compressedsprings which surround the shaft so that one is further compressed, inresponse to increased resistance to rotation of the worm gear, to permita surface on the cam to shift longitudinally into engagement with asensor which operates a switch to stop the motor.

Preferably, the shaft of the motor and the worm shaft are connected by apinion gear rotatable with the worm shaft and a spur gear on the motorshaft which maintains engagement with the first pinion gear despitelimited reciprocation of the worm shaft. Also, the worm shaft isreceived for reciprocation and rotation within spaced apart bearings inspaced walls of the housing, and the spring means are compressed betweenthe walls and ends of the assembly.

In the past, this movement of the worm shaft, and thus the torque cam soas to actuate the sensors or switches, has required complicated gearingbetween them and the shaft. Furthermore, the cam and sensors have beenof complex construction and difficult to install as well as adjust ormodify for different torque limits. Also, mechanisms of this type for sodeactivating the electric motor have not been supplied as optionalequipment--i.e., the actuator has either been provided with or withoutthe torque limiting mechanism. Still further, access to such priormechanisms for purposes of adjustment has been time consuming anddifficult.

It is an object of the invention to provide an actuator having a torquelimiting device of this type wherein the worm gear and worm shaft areeasily and quickly connected and installed, and, as will be described tofollow, are of such construction as to cooperate with a manual overridesystem including a handwheel selectively engagable with the shaft tooperate the valve upon deactivation of the motor. A still further objectis to provide such an actuator in which at least the sensors or switchesare easily installed as optional equipment, easily accessible forreplacement or repair, of simple and inexpensive construction, andeasily adjusted to deactivate the motor at desired torque levels.

In accordance with one novel aspect of the invention, the meansengagable by the torque cam to deactivate the motor in response toexcessive torque comprise a pair of keys each pivotally mounted on thehousing and having a finger which assumes a position opposite a camsurface, and a pair of switches each mounted in the housing in positionto be engaged by one of the fingers in order to deactivate the motor, asit is moved by the cam surface upon longitudinal movement of the wormshaft in opposite longitudinal directions in response to torque ofsufficient magnitude to overcome a predetermined force and thus shiftthe cam to one side of its neutral position.

Preferably, a lever is mounted on each of the keys to engage one of theswitches, when the key is so moved, with the keys being axially alignedand the sensors and arms being aligned on opposite sides of the keys. Asshown, a means is provided to easily and quickly adjust the location ofthe position of each key relative to the cam surface opposite itsfinger, and thus the torque at which the motor is deactivated.

In the illustrated and preferred embodiment of the invention, thehousing includes a base in which the motor and drive system includingthe torque cam is disposed, and a switch plate is releasably connectedto the base of the housing to cover the drive system. More particularly,the keys and switches of the torque limiting mechanism are mounted on abracket releasably connected to the wall to support the levers forextension through a hole in the switch plate into a position forengagement by the torque cam.

The manual override assemblies for prior actuators of this type havebeen of complicated and expensive construction, and, in some instances,have required complex gearing between the handwheel and the worm shaftto prevent rotation of the handwheel while the electric motor isactivated. It is therefore another object of this invention to provide amanual override which includes a unique arrangement for engaging withthe worm shaft of the drive system in any rotative position of thelatter, but disengagable therefrom to automatically deactivate the motoras the manual override is moved toward engaged position with the wormshaft. Thus, the manual override assembly includes a handwheel having amanual override shaft mounted in the housing in alignment with the wormshaft for rotation and reciprocation with respect thereto between firstand second longitudinal positions, means connecting the manual overrideshaft to the worm shaft in order to rotate the shaft, when the stem isin said first position, and for disconnecting the stem from the wormshaft, when in the second position, and means automatically responsiveto shifting of the manual override shaft toward its first position todeactivate the motor.

More particularly, the manual override shaft and worm shaft are of suchconstruction as to remain disconnected despite limited reciprocation ofthe worm shaft responsive to predetermined torque. Preferably, thehousing base has an internal cavity opening to one end, and the manualoverride assembly further comprises a liner in which the manual overrideshaft is carried and removably mounted within the cavity, theinstallation of the liner into the cavity serving to pre-compress thesprings and thus move the worm gear and cam to their neutral position.

In accordance with another novel aspect of the invention, the inner endof the manual override shaft includes a sleeve having longitudinalslots, and the adjacent end of the worm shaft has at least oneprotuberance for fitting within a slot, when the handwheel and manualoverride shaft are moved to one position, and for sliding out of theslot as they are moved to another position, so as to release the wormshaft for rotation, and means are provided for releasably holding themanual override shaft in each of its positions.

In accordance with still another novel aspect of the manual overrideassembly, a sensor of a switch is mounted on the housing, and a rodmounted in the switch for operation through holes in the switch plateand liner as well as in the sleeve on the outer end of the manualoverride shaft to dispose the inner end of the rod in the path of theshaft, as it is moved to the other position, to cause the switch todeactivate the motor, and disengaged thereby, when the manual overrideshaft is moved to its one position, to permit the motor to be activated.

It has also been proposed to automatically activate and deactivate theelectric motor of such an actuator by means of limit switches which areengaged by cams rotatable in response to rotation of the valve stembetween valve opened and closed position. It is often necessary toadjust the positions of the cams in order to adjust the opened andclosed positions of the valve. U.S. Pat. No. 5,305,781, assigned to theassignee of the present application, shows an arrangement of rotatablecams rotatable with the valve stem for engagement with switches toindicate the position of the valve at a remote location. The cams may beadjusted to different rotational positions by knobs which are readilyaccessible for manual manipulation at one end of the cams. A furtherobject of this invention is to adapt a similar arrangement of cams foruse in adjusting the open and closed positions of the valve at which themotor to be deactivated, and, more particularly, an actuator whichpermits access to the cams for adjustment merely upon removal of a coveradapted to be installed over for the base of the actuator housing.

Thus, in accordance with yet a further novel aspect of the invention,first and second axially spaced plates surround and are releasably fixedto a shaft rotatable with the valve stem, a first ring closely surroundsthe first plate for rotation with respect thereto and has a circle ofteeth formed about the interior thereof, and a second ring closelysurrounds the second plate for rotation with respect thereto and has acircle of teeth formed about its interior. More particularly, each ringhas an outer cam surface thereabout eccentric to its axis of rotation,and first and second switches are mounted on the switch plate in thehousing in position to be engaged and activated by the cam surfaces onthe first and second rings, respectively, during rotation of the shaftso as to stop the motor as the stem reaches open or closed position. Thepositions of the cams, and thus the starting and stopping of the motor,is easily adjusted by means of first and second rods mounted on theplates for rotation about axes parallel to the axis of rotation of theshaft, a pinion gear on the first rod engaging the circle of teeth ofthe first ring, a pinion gear on the second rod engaging the circle ofteeth of the second ring, and manually manipulative means on the ends ofrods outwardly of one of the plates so as to permit adjustment of therotation position of the cam surfaces by knobs which are accessible uponremoval of the cover.

In prior actuators of this type, it has been proposed to sense theposition of the disc or other valve member by means of a potentiometerso that a signal representative of the position may be electricallytransmitted to a location remote from the valve. For this purpose, theteeth of a pinion rotatable with an external portion of the shaft of thepotentiometer on which its wiper blade is secured are engaged by a drivegear mounted for rotation in the actuator housing in response torotation of the valve between open and closed positions. Since apotentiometer has a useful range through only about 270° of rotation ofits shaft, the gear teeth are so related as to rotate the potentiometershaft through this range in response to only a quarter turn or otherrange of opening and closing movement of the valve.

However, the interengagement between the drive gear and potentiometershaft requires careful adjustment to insure accurate results and avoiddamage to it by forcing its wiper blade beyond its useful range in onedirection or the other. In the past, this has required that the userobtain access to the potentiometer within the actuator housing to adjustset screws which hold the drive gear in a desired rotational positionwith respect to the potentiometer shaft. One of the objects of thisinvention is to provide such a valve position indicator which is easy toadjust without risk of damage to the potentiometer, and further in whichthe desired position of the teeth on the potentiometer gear of thepotentiometer shaft are automatically determined upon assembly withoutthe need for set screws and the like.

Thus, as in prior actuators of this type, the position of the valve stemis indicated electronically by a potentiometer having a shaft forrotating a pointer past a wiper ring throughout its useful range, and apotentiometer gear about an external portion of the potentiometer shaftand engaging a drive gear rotatable with the valve stem so as to rotatethe pointer in response thereto. However, in accordance with anotheraspect of the invention, a portion of the periphery of the potentiometergear is free of teeth so that it will not be rotated beyond the usefulrange of the potentiometer. Thus, the remaining periphery is flat sothat the drive gear merely passes by the potentiometer gear on the shaftand not continue to rotate it beyond the useful range of thepotentiometer. More particularly, a means for adjusting the rotativeposition of the drive gear and thus the potentiometer shaft isaccessible upon removal of the housing cover. Preferably, the shaft ofthe potentiometer is out of round for fitting closely within an out ofround hole in the potentiometer gear so as to fix their rotationalpositions with respect to one another.

More particularly, the above mentioned means for adjusting thepotentiometer is integrated with the above-described arrangement fordeactivating the motor in that the drive gear surrounds a third platewhich is fixed to the shaft rotatable with the valve stem and in axiallyspaced relation to each of the first and second plates, to dispose teethformed about its exterior in position to engage the gear teeth on thepotentiometer shaft. More particularly, a third rod is mounted on theplates for rotation about axes parallel to the axis of rotation of theshaft, a pinion gear on the third rod engages an inner circle of teethof the ring gear, and means are provided on the end of the third rodoutwardly of the one plate for manual manipulation so as to permitadjustment of the potentiometer shaft.

It is also preferred to provide such an actuator with a means forvisually indicating the position of the valve, particularly in itsopened and closed positions, which is located at or near the valve.Prior indicators have been proposed in which an inner cylinder rotatablein response to the valve stem, and having "opened" and "closed"indicators about its circumference which are representative of theposition of the valve, is disposed within an outer cylinder havingtransparent windows arranged to permit viewing of the indicia from mostany location about the valve. In prior actuators, however, theseindicators have been difficult to install and to remove for replacementor repair.

In accordance with still another novel aspect of the invention, theposition of the valve is indicated by means which includes an opening inthe cover opposite one end of the shaft rotatable in response torotation of the valve stem, and an outer cylinder having detent fingersfor passing yieldably through the hole and means thereon engagable withthe outer side of the wall when the detent fingers are engaged with theinner side thereof about the hole, and an inner cylinder for releasablyengagement with the shaft for rotation therewith and disposal within theouter cylinder, the outer cylinder having transparent windows and theinner cylinder having indicia thereabout visible through the windows forindicating the disposal of the valve in open and closed positions. Moreparticularly, the means engagable with the outer wall includes a flangeabout the outer cylinder having a groove and a seal of resilientmaterial carried within and protruding from the groove to form a sealwith the outer wall of the housing and maintain the detent fingerstightly against the inner side of the wall.

As shown, the worm gear connectable to the valve stem so as to rotatethe valve between open and closed positions has shoulders at oppositeends of a partial circle of teeth for engaging the worm, and stops aremounted on and extend into the housing in position to be engaged by theshoulders to prevent over travel of the gear in either direction. Moreparticularly, the stops are threaded to the housing so that they may beadjusted from outside the housing to move their surfaces to positionsfor engagement by the shoulders in different rotational positions of thegear.

As above-described, those parts of the actuator which seldom requirerepair or adjustment, such as the motor, worm gear, and worm shaft withworm gear and cam thereon are mounted within the base of the housingbeneath the switch plate. Those parts, such as the potentiometer, torquelimit keys, and various switches, which require more frequent adjustmentor repair, are above the switch plate and thus accessible merely uponremoval of the cover. Furthermore, since the handwheel and related partsof the override assembly are quickly and easily assembled within thecavity in an outer wall of the housing, the assembly may, like thetorque sensing keys, be an optional feature.

In the drawings, wherein like reference characters are used throughoutto designate like parts:

FIG. 1 is an end view of an actuator constructed in accordance with thepresent invention and mounted on a butterfly valve for use in moving thedisc thereof between opened and closed position;

FIG. 2 is a view of the actuator and valve of FIG. 1 as seen from theright-hand side thereof;

FIG. 3 is top view of the actuator, on an enlarged scale, with the coverremoved from the base of the housing, as seen along broken lines 3--3 ofFIG. 1; and with the handwheel withdrawn to move the manual drive systemto engaged position;

FIG. 4 is another top view similar to FIG. 3, but with the inner wall(switch plate) removed from over the upper open end of the base of thehousing;

FIG. 4A is a cross-sectional view of the manual override assembly, on anenlarged scale and as seen along broken lines 4A--4A of FIG. 4;

FIG. 5 is a vertical sectional view of the actuator, on an enlargedscale, and as seen along broken lines 5--5 of FIG. 6;

FIG. 5A is a cross-sectional view of the potentiometer and the drivegear for operating the potentiometer gear on its shaft, on an enlargedscale, and as seen along broken lines 5A--5A of FIG. 5B;

FIG. 5B is a vertical sectional view of the potentiometer and drivegear, as well as the cams for engaging the limit switches for stoppingthe motor in each of its valve opening and closing positions, as seenalong broken lines 5B--5B of FIG. 5A;

FIG. 6 is an enlarged vertical sectional view of the actuator, as seenalong broken lines 6--6 of FIG. 5;

FIG. 7 is a view of the actuator, partly in plan and partly inelevation, as seen generally along broken lines 7--7 of FIG. 5, showingthe worm and override cam in neutral positions, as in FIG. 5, and thusduring operation of the valve in the absence of excessive torque, shownwith override engaged;

FIG. 8 is a view similar to FIG. 7, but wherein excessive torque, duefor example to an obstruction in the line of the valve, has moved theworm and cam right to rotate one of the sensing fingers and thusdeactivate the motor, shown with override engaged;

FIG. 9 is an enlarged view of the torque sensing mechanism, as seenalong broken lines 9--9 of FIG. 11, and showing its fingers in adependent position opposite cam surfaces on the cam carried by the worm;

FIG. 10 is a view similar to FIG. 9, but wherein the cam has beenshifted with the worm to the right so as to engage and move the fingerof the left-hand sensing key in order to deactivate the motor, as shownin FIG. 8;

FIG. 11 is a view from the bottom of the torque sensing device, asviewed along broken lines 11--11 of FIG. 9;

FIG. 12 is a diagram of the electrical wiring within the actuator,showing its connections to various switches as well as a diagrammaticillustration of the pointer and wiper blade of the potentiometer; and

FIG. 12A is another diagrammatic illustration of the pointer and wiperblade with the pointer moved to another position responsive to rotationof the ring gear fixed to the shaft rotatable with the valve stem.

With reference now to the details of the above-described drawings, theactuator, which is designated in its entirety by reference character100, is shown in FIGS. 1 and 2 mounted on a butterfly valve indicated inits entirety by reference character 101. As also shown therein, thebutterfly valve comprises a body 102 having a passageway 103therethrough connected in alignment with a pipeline 104 or other flowconduit, and a disc 105 on mounted for rotation a quarter turn or 90°within the valve body between opened (FIG. 1) and closed positions.

A stem 106 for rotating the disc is connected thereto at its lower endand extends upwardly through a neck 102A of the valve body forconnection at its outer end with a drive mechanism within the actuatorfor so rotating the valve stem and the disc. A flange 107 on the valvebody neck is connected to the lower side of a base 111 of the housing110 of the actuator by bolts or other suitable means, and a cover 112 isreleasably connected over the open upper end of the base.

The base of the housing is a casting having a boss 113 on its bottomwall on which a worm gear 114 of the drive mechanism of the actuator ismounted. The worm gear in turn has a sleeve 114A extending downwardlyfrom its lower side and closely into the boss in position to receive theupper end of the stem of the valve. The ends of the stem and sleeve havemating non-circular surfaces which permit the worm gear to impart rotarymotion to the valve stem in opposite directions. The worm gear is helddown in supported position on the boss by means of a washer 114Bretained by a snap ring about the lower end of the sleeve.

The worm gear and thus the valve stem are adapted to be rotated inopposite directions in response to a reversible electric motor M whichis connected to the worm gear by a worm 115 carried by a worm shaft 116supported in the housing for rotation and longitudinal reciprocationtraversely of the axis of rotation of the worm gear. Thus, the shaft isreceived through and supported toward opposite ends by means of bearings118 and 119 mounted within openings in spaced apart upstanding walls onthe lower side of the housing base. The worm is connected to the shaftby a pin 117 which extends through them.

A spur gear 120 is releasably connected to the end of the shaft 116 fordriving connection with a motor gear 121 driven by the output shaft ofthe motor, as shown in FIG. 4, whereby operation of the motor in onedirection will in turn rotate the worm shaft, worm and worm gear, andthus the valve stem, in one direction, while operation of the electricmotor in the opposite direction will in turn rotate the valve stem inthe opposite direction, thus selectively moving the valve between openedand closed positions. In a manner to be described to follow, the wormand the shaft on which its mounted, are free to move longitudinally alimited extent, and, for this purpose, and again as shown in FIG. 4, themotor gear 120 is sufficiently wide to maintain driving engagement withthe spur gear 120 on the worm shaft during any such movement.

A manual override system for the actuator is mounted on the housing baseat the right-hand end of the worm shaft 115 and includes an externalhandwheel 125 mounted on the outer end of a stem 126 whose inner end isin turn mounted for reciprocation within a cavity 127 formed in theright-hand end of the housing base for shifting between an innerposition (FIG. 5) in which the manual override is disengaged and anouter position (FIGS. 7 and 8) in which the manual override is engaged.More particularly, the right-hand end of the-worm shaft and the innerend of the stem are so constructed that, as will be described to follow,the shaft is free to move a limited extent longitudinally withoutengaging the manual override during the electric motor driven sequenceof the actuator.

As best shown in FIGS. 5, 7 and 8, the manual override system includes aliner 130 which is releasably held within the cavity 127 in theright-hand of the housing base by means of a snap ring 131, andsurrounds a sleeve 132 on the inner end of the stem by means of a pin133 extending through them. Alternatively, the sleeve may be an integralpart of the stem. More particularly, the sleeve is of a size to receivethe right-hand end of the worm shaft, and the liner engages a shoulderon a plate 138 within the cavity to locate bearing 119 through which theright-hand end of the worm shaft extends.

The handwheel 125 is held in either of its engaged or disengagedpositions by means of ball detents 135 which are spring pressed into oneof longitudinally spaced grooves 136 and 137 about the inner diameter ofthe liner. Seal rings are disposed about the outer and inner diametersof the outer end of the liner to prevent the passage of debris into theinterior of the actuator.

As best shown in FIG. 4A, the inner diameter of the sleeve has a seriesof arcuate slots 140 formed about its left-hand end, and a pin 141 isslidably received through the right-hand end of the worm shaft todispose its outer protruding ends in position to fit within radiallyopposite slots in the sleeve. When the handwheel is pulled outwardly, asshown in FIGS. 7 and 8, the ends of the pin fit within a pair of theslots so as to provide a rotary driving connection between the handwheeland worm shaft for in turn manually driving the worm gear and thusrotating the valve stem. However, upon inward movement of the handwheeland stem, the drive pin moves out of the slots, as shown in FIG. 5, tofree the worm shaft 116 from rotation by the handwheel.

The manual override system also includes a means for automaticallydeactivating the electric motor prior to movement of the override intoits engaged position. For this purpose, a switch 145 is mounted abovethe upper side of the base of the actuator housing in position to beactuated so as to deactivate the motor as the override shaft 132 ismoved outwardly with the handwheel to the position of FIGS. 7 or 8.Then, upon return of the override shaft to its inner position disengagedwith the worm shaft, the sleeve 132 will trigger the switch so that itwill be positioned for again deactivating the motor in the event theoperator decides to engage the manual override. The switch is mounted ona bracket which in turn is mounted on an inner wall 147 of the housingwhich is bolted or otherwise secured to the open upper side of thehousing base to cover a recessed portion of the housing base. As alsopreviously described, it serves as a switch plate, and with other wallsof the housing base, encloses a lower compartment below it for thoseparts not normally requiring access by the operator and with the cover112, and upper compartment enclosing those parts which may requireadjustment or repair, merely upon removal of the cover 112.

The switch itself is adapted to be activated by a rod 148 which extendsthrough aligned holes in the inner wall and housing base as well asthrough the liner 130 to dispose its lower end for engagement by theoverride shaft 132. Thus, the rod is held upwardly by the override shaftwhen the manual override is in its disengaged position, to close theswitch so as to enable the motor to operate. On the other hand, when thesleeve is shifted to the right by movement of the handwheel to engagedposition, the rod is spring pressed downwardly to open the switch. Theend of the override shaft is beveled to facilitate its cooperation withthe inner end of the rod.

As will be seen from a comparison of FIGS. 7 and 8, the pin 141maintains its engagement with a pair of slots despite limitedlongitudinal movement of the worm shaft with respect to the housing, andthus with respect to the manual override shaft which is mounted in thehousing, in response to excessive torque, as will be better understoodfrom the description to follow.

The worm shaft is also surrounded by a cam 150 which, as shown, isformed integrally with the right end of the worm, although it may beseparate therefrom, so that it, like the worm, is fixed to the shaft.The worm shaft is also surrounded by two sets of Bellville springs 151,one of which is precompressed between the left-hand end of the worm andthe wall of the housing base in which the left bearing 118 is mountedand the other of which between the right-hand end of the cam and theright-hand bearing 119 mounted in the opposite wall of the actuatorhousing base.

As previously described, during normal operation of the actuator, thesesprings are precompressed to maintain the worm and cam, and thus theworm shaft to which they are fixed, in a "neutral" position wherein eachset of springs is equally compressed. However, in the event the valveencounters excessive torque, as for example when there is an obstructionin the line, the resulting resistance to rotation is transmitted throughthe worm and cam to cause one of the sets of the springs to be furthercompressed, such as the right-hand set shown in FIG. 8, in the event ofa resistance of opening movement of the valve. On the other hand, in theevent the resistance is closing the valve, the left-hand set of springsmay be compressed.

In the assembly of the valve, with the manual override system removedfrom the cavity in the base of the housing, the worm and cam, togetherwith both sets of springs, are axially aligned with the spaced bearingsin the housing to permit the worm shaft 116 (with the spur gear 120removed from its left end) to be inserted through the cavity, right-handbearing, worm, cam, springs, and left-hand bearing. Thus, uponinstallation of the manual override system, bearing plate 138 at theleft end of the sleeve and liner 130 will apply force to the right-handbearing 119 to compress the springs so that, upon connection of theliner in the cavity, the worm and cam are held in a neutral position.

All of this is done, of course, prior to installation of the worm gearinto engagement of the worm, and, of course, optional installation ofthe torque limiting sensors (to be described) into the positions shownin FIGS. 5, 7 and 8, from above the inner wall of the housing. Also, ofcourse, the spur gear 120 would be connected to the left end of the wormshaft for driving engagement with the gear of the motor.

As previously described, the means for deactivating the motor, and thuspreventing destruction of the obstructed valve disc, in response to apre-determined torque, comprises tapered cam surfaces 155A and 155B (seeFIGS. 9 to 11) about the cam, and a pair of keys 160A and 160B mountedon a bracket B secured to the inner wall of the housing. A finger of onekey is thus disposed in position to be engaged by one cam surface, inthe event of excessive torque during movement of the valve stem in onedirection, and the other to be engaged by the other cam surface in theevent of excessive torque during movement of the valve stem in theopposite direction. More particularly, a pair of switches 161A and 161Bare also mounted on the bracket each in position to be engaged by one ofthe keys so as to deactivate the motor when the finger of that key ispivoted to a predetermined extent due to engagement therewith of one ofthe cam surfaces.

Thus, the bracket B is disposed over an opening 162 formed in the innerwall of the base of the housing to permit the fingers of the keys todepend therethrough into positions intermediate the cam surfaces on thecam, as shown in FIGS. 9 to 11. More particularly, each key is pivotallymounted on the bracket by a pin 163 extending therethrough and mountedat opposite ends on opposite walls 164 of the bracket. The switches arefixedly mounted on the bracket by means of pins 165 which extend throughthem and the opposite walls of the bracket each, with a button 166thereon disposed for engagement with a key as the key is pivoted apredetermined extent by one of the cam surfaces.

Thus, as shown in FIG. 11, the keys and switches are laterally spacedapart with each being adjacent to one side wall of the bracket. Leverarms 167A and 167B are disposed about the key shafts intermediate thekeys and switches, so that a free end thereof is disposed beneath aswitch button, as shown in FIG. 9, when the arm is unstressed, so thatthe finger is merely disposed in position to be engaged by a camsurface. However, when the key is pivoted upon engagement of the camsurface with its finger, the free end of the arm is moved upwardly todepress the switch button and thus activate the switch, when the key hasbeen swung to a predetermined extent by the longitudinal movement of thecam surface with the worm shaft, and thus deactivate the motor. Asshown, the arms are aligned so as to minimize the width of the bracket.

As also shown, the end of each lever arm is disposed opposite a screw168 mounted on each key, whereby the screw may be adjusted to adjust theforce at which the switch engaged by the arm is activated.

As also previously described, one of the novel features of the presentinvention is the ability of the user of the actuator to eitherincorporate or do without the above described mechanism for deactivatingthe motor in the event of excessive torque. Thus, if it is to be used,it is merely necessary to mount the bracket in the position shown andreleasably connect it to the inner wall by means of screws, thus movingthe depending fingers of the keys through the hole in the inner wallinto positions opposite the cam surfaces. If this torque limitingfeature is not to be used, the combined cam and worm could be replacedby a worm, and the bracket with the sensing fingers would not beinstalled. A blank bracket could be used to cover the opening in theswitch plate. As shown, the bracket for the shut off switch 145 of themanual override mechanism is also mounted on the flange on the samebracket.

As best shown in FIG. 4, gear teeth are disposed only about that portionof the worm gear 114 which, during operation of the actuator, is engagedby the worm on the worm shaft. Shoulders 170 and 171 are formed onperipherally spaced portions of the remainder of the circumference ofthe worm gear at opposite ends of the teeth in position to be engaged bythe inner ends of bolts 172 and 173 threadably connected through holesin one side of the base of the actuator housing. As shown in FIG. 4,these bolts are held in place by nuts which permit the user of theactuator to adjust the inner ends of the screws, and thus the positionsat which the worm gear, and thus the stem of the valve would be stoppedin an emergency situation--i.e., in which the actuator was otherwisefree to continue to rotate the valve stem beyond its desired open orclosed position.

As previously described, switches are mounted within the actuator inposition to be actuated so as to deactivate the motor, in response torotation of the valve stem and thus the valve member into one of itspositions. More particularly, and as best shown in FIGS. 3 and 5, upperand lower limit switches 175 and 176 are mounted in vertically spacedrelation on the inner wall of the base of the housing with sensorsthereon disposed opposite similarly spaced upper and lower cam rings 177and 178, respectively, surrounding and rotatable with an upper shaft 180rotatable with the gear 114 of the drive mechanism, and thus in directresponse to rotation of the valve stem. As shown in FIG. 5B, this camshaft extends closely through a sleeve 181 in the inner wall 147 forreleasable connection at its lower end to the worm gear. Thus, the upperside of the worm gear has a slot 182 which is adapted to closely receivea tongue 183 on the lower end of the cam shaft so that the shaft and camrings mounted thereon may be removed or replaced from within the upperhousing compartment without removing the inner wall.

As shown, each of the cam rings has a cam surface 177A and 178A formedabout its periphery opposite one of the limit switches. With the valvebeing rotatable a quarter of a turn, these cams have their high sidesrotationally displaced about 90°. Assuming that the upper cam ring 177is the valve closing cam, and as shown in FIG. 5, its high point willactivate the upper limit switch 175 as the valve is moved to openposition in response to rotation of the worm gear with the valve stem inone rotational direction. Then, upon return movement of the valve to itsclosed position, the high point on the lower cam ring 178 will moveapproximately 90° so as to actuate the lower switch 176 for deactivatingthe motor as the valve reaches its closed position in response torotation of the worm gear with the valve stem in the opposite rotationaldirection. As indicated on the diagram, the switches may be closed toreactivate the motor and thus return the valve to open or closedposition, by switches activated externally of the actuator.

As previously described, this assembly for actuating the limit switchesis similar in construction to that shown in the aforementioned. U.S.Pat. No. 5,305,781 wherein similar cam rings are used to supply anindication of the position of the valve at a remote location. Hence, asin the prior patent, it provides a unique arrangement for independentlyadjusting the rotational position of each cam ring, when required,merely upon removal of the cover of the housing from the base thereof.Thus, the cam rings are supported on and rotatable with the cam shaft180 and have gear teeth 190A and 190B about their inner periphery whichare engaged with pinion gears mounted on rods 191A and 191B extendingupwardly to knobs 192A and 192B on the upper end of the assembly, theknobs thus providing a means which the cam rings may be manuallyadjusted. The rods also extend through plates 193A and 193B which arefixed to the shaft by pins 194A and 194B and through which the rodsextend. More particularly, these plates are disposed above and beloweach of the cam rings and are received through recesses in spacer platesdisposed between the other plates.

As also previously described, the location of the valve is adapted to beremotely observed by a means which includes a potentiometer 200 mountedon the inner wall 147 of the base of the housing by means of a bracket201 releasably connected thereto, and a potentiometer gear 202 rotatablewith the external lower end of the potentiometer shaft 203 for movementby a drive gear 204 disposed opposite thereto and rotatable in responseto the valve stem. More particularly, in accordance with another novelaspect of the invention, this drive gear 204 is mounted on the sameshaft 180 on which the cam rings are mounted by a plate 205 which itclosely surrounds and which is fixed to the shaft by means of a pin 207.Teeth formed about the inner periphery of drive gear 204 engage a piniongear 208 which is mounted on the lower end of a rod 209 which, like thecam ring adjusting rods, extends between a knob 210 on its upper end andthe pinion gear which rotates within in a recess in a spacer plate abovethe mounting plate 205 and below the spacer plate for the lower cam ring178. This then permits the ring gear to be rotated in either directionfrom a readily accessible location above the inner wall of the base ofthe housing, and thus to correct any out of adjustment of thepotentiometer without the need for access to and manipulation of setscrews and the like, as was the case in the prior art.

The container for the potentiometer, which is properly oriented on thebracket by a tab on its side adapted to fit closely within a slot in thebracket, may be of conventional construction having, as showndiagrammatically in FIGS. 12 and 12A, a wiper ring 220 over which apointer 221 mounted on the potentiometer shaft 203 is adapted to move tovary the output of the potentiometer and thus remotely indicate theposition of the valve. For this latter purpose, the end of thepotentiometer shaft has a flat side 222 (FIG. 5A) forming an out ofaround configuration adapted to fit closely within a hole in thepotentiometer gear rotatable with the shaft so as to permit the pointerto properly relate the wiper to the rotational position of the valve.

As previously indicated, and as well known in the art, a potentiometerhas a useful range of only about 270°. Thus, in response to rotation ofthe valve 90° between open and closed positions, the pointer will swingthrough approximately 270°. This is accomplished of course by a suitableratio between the teeth of the ring gear to those on the pinion gear onthe shaft of the potentiometer.

In accordance with another novel aspect of the invention, the side F ofthe partial gear on the potentiometer shaft is flat intermediate theteeth thereabout adapted to engage the ring gear during rotation of thepointer throughout the active range of the potentiometer. As a result,the partial gear cannot rotate the potentiometer out of its activerange, since its teeth will first move out of engagement with thepotentiometer gear. This, of course, is true of rotation of the partialgear whether during opening or closing of the valve. As previouslydescribed, this eliminates the possibility of a false signal emanatingfrom the valve actuator.

The means for indicating the position of the valve at or about itslocation comprises an inner cylinder 230 having "opened" and "closed"indicia about its circumference and its upper conical end and releasablymounted on the upper end of the shaft 180 on which the above describedcam rings are mounted. An outer cylinder 231 is mounted on the top wallof the cover of the housing in position to surround the inner cylinderto permit viewing of the indicia on the inner cylinder. Thus, as shown,the outer cylinder has windows so arranged about its circumference, aswell as about its conical upper end, as to permit the viewer to observethe position of the valve as indicated by the position of that indiciain response to rotation of the shaft, as shown in FIGS. 5 and 6.

More particularly, the inner cylinder has a stem 232 on its lower endhaving transverse slots adapted to closely receive transverseprotrusions at the upper end of the shaft 180 on which the cam rings andgear ring are mounted to cause it to be rotated with the shaft and thuswith the valve stem. Thus, the lower end of the inner cylinder maymerely be moved downwardly through an opening 233 to engage the upperend of the shaft which automatically coordinates the "opened" or"closed" indicia thereon with corresponding positions of the valve.Obviously, other indicia may be used to indicate open or closedpositions. The cylindrical and upper conical portions of the outerhousing fit closely to corresponding portions of the inner cylinder whenthe outer cylinder is releasably mounted on the cover of the housing,and with the windows arranged opposite the indicia. For this latterpurpose, the lower end of the outer housing has spring fingers 240 ordetents adapted to fit closely through the opening in the cover topermit their lower ends 241 to snap beneath the inner side of the coveras they move through the opening in the cover. More particularly, thereis a flange 242 about the outer housing which engages its upper side asthe detents move into position.

There is a flange which contains an elastic seal ring 243 of such sizeas to normally protrude from the lower side of the flange. Thus, itserves not only to form a seal or at least a debris barrier between theouter cylinder and the cover, but also to yieldably urge the outercylinder upwardly and thus hold the detents tightly engaged with theinner side of the cover.

As shown in FIG. 3, the base of the housing includes a second inner wall244 which is disposed over the lower compartment of the base not coveredby the first inner wall. This wall, like the first wall, is adapted tobe fastened to the open upper end of the base. It has banks of switchesmounted thereon and serves, along with the other inner wall, to separatethe upper and lower compartments of the housing from one another, and,more particularly, to enclose certain of the more permanent componentsof the actuator, including the motor and associated wiring. The wall147, when in place, covers other parts which do not require frequentreplacement, such as the worm shaft, worm and cam, as well as theBellville springs mounted on the shaft, the worm gear, and the stops.Parts of the actuator which, on the other hand, may require adjustment,are accessible for that purpose above the inner walls when the cover isremoved from the housing base. This, of course, includes the knobs onthe upper ends of the rods leading to the cam rings as well as the drivegear for adjusting the potentiometer, the torque sensing apparatus, thepotentiometer itself, as well as the safety switch and limit switches.

The wiring diagram of FIG. 12 includes a diagrammatic illustration ofthe partial gear on the potentiometer shaft and the drive gear foradjusting the potentiometer, as well as the proximity switchesresponsive to the opening and closing cams, and the switches responsiveto the torque response keys. FIG. 12A shows the partial gear of thepotentiometer shaft moved from the position of FIG. 12. Wiring is alsoshown for connecting the potentiometer to a remote position indicatorextension of the housing.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages which are obvious and which are inherentto the apparatus.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

What is claimed is:
 1. A rotary valve actuator, comprisinga housingadapted to be mounted on the valve and having an opening in an outerwall thereof, means within the housing for rotating the valve stembetween positions opening and closing the valve, including a shafthaving one end mounted opposite the housing opening and rotatable inresponse to rotation of the stem, an outer cylinder having detentfingers for passing yieldably through the opening and means thereonengagable with the outer side of the outer wall, when the detent fingersare engaged with the inner side thereof about the opening, and an innercylinder within the outer cylinder releasably engaged with the one endof the shaft for rotation therewith, said outer cylinder having windowsand said inner cylinder having indicia thereabout visible through thewindows for indicating the disposal of the valve in open and closedpositions.
 2. As in claim 1, whereinthe means engagable with the outerside of the outer wall includes a flange about the outer cylinder, and aseal of resilient material protrudes to form a seal with the outer sideof the outer wall of the housing and maintain the detent fingers tightlyagainst the inner side of the wall.
 3. A rotary valve actuator,comprisinga housing adapted to be mounted on the valve, means within thehousing for rotating the valve stem between opened and closed positions,a shaft rotatable with the stem and having a drive gear thereabout, andmeans for indicating the position of the valve stem, including apotentiometer having a shaft for rotating a pointer past a wiper ringthroughout its useful range, and a potentiometer gear arrangedsymmetrically about a portion of the potentiometer shaft for rotationtherewith and having teeth for engaging the drive gear on the shaft soas to rotate the pointer in response to rotation of the shaft, theremainder of the periphery of the potentiometer gear being free of teethso that it will not be rotated by the drive gear beyond the useful rangeof the potentiometer.
 4. As in claim 3, whereinthe shaft of thepotentiometer is out of round for fitting closely within an out of roundhole in the potentiometer gear so as to fix their rotational positionswith respect to one another.
 5. As in claim 4, includingmeans foradjusting the rotative position of the potentiometer ring about theshaft.
 6. A rotary valve actuator, comprisinga housing having a baseadapted to be mounted on the valve, a reversible electric motor mountedfor rotation in the housing base, means for rotating the valve stembetween valve open and closed positions in response to operation of themotor in opposite directions, and means for starting and stopping themotor in the opened and closed positions of the valve, including a shaftrotatable with the stem, first and second plates surrounding andreleasably fixed to the shaft in axially spaced relation, a first ringclosely surrounding the first plate for rotation with respect theretoand having a circle of teeth formed about the interior thereof, a secondring closely surrounding the second plate for rotation with respectthereto and having a circle of teeth thereabout, each ring having anouter cam surface eccentric to its axis of rotation, first and secondswitches mounted in the housing in position to be engaged and activatedby the cam surfaces on the first and second rings, respectively, duringrotation of the shaft, so as to stop the motor in opened and closedpositions of the valve, and first and second rods mounted on the platesfor rotation about axes parallel to the axis of rotation of the shaft, apinion gear on the first rod engaging the circle of teeth of the firstring, a pinion gear on the second rod engaging the circle of teeth ofthe second ring, and manually manipulative means on the ends of rodsoutwardly of one of the plates so as to permit adjustment of therotation position of the cam surfaces on the rings, and including meansfor indicating the position of the valve, comprising a third platesurrounding and fixed to the shaft in axially spaced relation to each ofthe first and second plates, a third ring closely surrounding the thirdplate for rotation with respect thereto and having a circle of teethformed about the interior thereof, a potentiometer mounted in thehousing and having teeth about its shaft which are engaged with theteeth about the third ring so that a pointer on the shaft is rotatedpast a wiper ring a distance indicative of the position of the valve, athird rod mounted on the plates for rotation about axes parallel to theaxis of rotation of the shaft, a pinion gear on the third rod engagingthe circle of teeth of the third gear, and manually manipulatable meanson the end of the third rod outwardly of the one plate so as to permitadjustment of the position of the pointer relative to the wiper.
 7. Arotary valve actuator, comprisinga housing having a base adapted to bemounted on the valve, an interior wall disposable over an open end ofthe base, and a cover removably mounted on the base to provide access tothe housing above the inner wall, a reversible electric motor and adrive assembly within the housing base beneath the inner wall forconnecting the motor to the valve stem, means including a potentiometerfor indicating the position of the valve, means for adjusting the rangeover which the potentiometer operates, and means for deactivating themotor when the valve stem reaches its opened and closed positions, andmeans for adjusting the positions at which the motor is deactivated inresponse to excessive torque, each of said potentiometer, motordeactivating means, and adjusting means being disposed on the upper sideof the inner wall for access upon removal of the cover.
 8. A rotaryvalve actuator, comprisinga housing having a base adapted to be mountedon the valve, a reversible electric motor mounted for rotation in thehousing base, means for rotating the valve stem between valve open andclosed positions in response to operation of the motor in oppositedirections, and means for starting and stopping the motor in the openedand closed positions of the valve, including a shaft rotatable with thestem, first and second plates surrounding and releasably fixed to theshaft in axially spaced relation, a first ring closely surrounding thefirst plate for rotation with respect thereto and having a circle ofteeth formed about the interior thereof, a second ring closelysurrounding the second plate for rotation with respect thereto andhaving a circle of teeth thereabout, each ring having an outer camsurface eccentric to its axis of rotation, first and second switchesmounted in the housing in position to be engaged and activated by thecam surfaces on the first and second rings, respectively, duringrotation of the shaft, so as to stop the motor in opened and closedpositions of the valve, and first and second rods mounted on the platesfor rotation about axes parallel to the axis of rotation of the shaft, apinion gear on the first rod engaging the circle of teeth of the firstring, a pinion gear on the second rod engaging the circle of teeth ofthe second ring, and manually manipulative means on the ends of rodsoutwardly of one of the plates so as to permit adjustment of therotation position of the cam surfaces on the rings.
 9. As in claim 8,whereinthe shaft has a pair of holes therethrough, the plates have holestherethrough aligned with the holes in the shaft, and pins are receivedin the holes to fix the plates to the shaft.